TO HIS family, Harry Allen was a kindly grandad – for many condemned prisoners he was the last face they ever saw. Now his private diaries are up for sale.

There is a common myth that Britain’s last hangman was Albert Pierrepoint, the country’s most prolific executioner, whose fame was enhanced with the release two years ago of a film biography starring Timothy Spall.

But Pierrepoint, whose father and uncle were also hangmen, didn’t carry out Britain’s last execution. That dubious honour went jointly to Harry Allen and Robert Stewart, who hanged a pair of murderers in simultaneous executions at different ­prisons in 1964.

Allen, who started his career as Pierrepoint’s deputy, put to death a killer called Gwynne Evans in his 29th execution.

He had previously also hanged James Hanratty, whose controversial execution in 1962 paved the way for the abolition of the death penalty.

EXECUTED: Allen hanged James Hanratty

He had assisted at 53 more, including that of Derek Bentley, who was convicted of murdering a policeman even though did not fire the fatal bullet and was given a posthumous pardon in 1998.

A fascinating insight into Allen’s macabre world has just been revealed through his private diaries and a collection of mem­orabilia and tools of the trade – including two of the black bow- ties he wore at every execution – which have just been put up for auction by his widow, Doris.

In his public pronouncements Allen, who died in 1992 aged 81, insisted that hanging was a swift and humane business. “I would always sneak a look at the condemned man in the exercise yard,” he said.

He always insisted hanging was humane

“It was crucial to know the height and weight for a quick and painless death. Then we did a test using a sandbag to see how much rope to use. If the drop was too long for the weight, it would pull the head off.

“From walking into the condemned cell to the prisoner being certified dead was around 15 seconds. I would say good morning and tie his arms behind his back. Then the door to the execution chamber opened and he took his place on the scaffold. While my assistant tied his legs, I placed the hood on his head and the rope around his neck. In seconds the lever was pulled.

“It’s a myth that prisoners struggle on the end of the rope, or that their hearts go on beating for some time. They die instantly and painlessly.”

But his private diaries tell a slightly different story. Reflecting on one execution, Allen wrote: “Very good job but should have had another two or three inches – very strong.” And he admits that another condemned prisoner – a 22-year-old child rapist and murderer called Peter Griffiths – was still alive 30 seconds after the trapdoor opened.

Allen was 29 when he witnessed his first execution – that of William Cooper, hanged in November 1940 at Bedford prison. He described it as a “very clean job” despite the condemned man’s “loss of courage”. He noted: “The culprit had to be carried to the scaffold owing to his faintness.”

He also hanged Derek Bentley, who was given a posthumous pardon in 1998

But later, he saw prisoners go to their death with a smile. He recorded that one man, a 24-year-old soldier called Clifford Holmes, seemed “very cheerful” moments before he was hanged at Strangeways in February 1941. Holmes had murdered his wife for having an affair while he was away in the army.

In public, Allen described the executions as a job of work. “Afterwards I would wash and change and have breakfast. Quite often I had to buy an evening paper to find out who I had hanged,” he said.

But his private papers reveal that he was not always dispassionate. In 1945 he executed five German prisoners of war who had murdered a fellow prisoner for alerting their British jailers to an escape attempt. He wrote: “It was a foul murder. They staged a mock trial, kicking the victim to death and dragging him by the neck to the toilet where they hung his lifeless body on a waste pipe. These five prisoners are the most callous men I have ever met so far but I blame the Nazi doctrine for that. It must be a terrible creed.”

CONNECTION: Fiona Allen recalls her famous grandad with fondness

In addition to the journals, the effects for sale include a scrapbook of cuttings, a tape measure used for measuring bodies and the length of the drop, a pair of pliers for attaching lead weights to the gallows and the watch with which Allen timed the hangings.

As well as undertaking one of Britain’s final hangings, Allen performed the last execution in North­ern Ireland, of Robert McGladdery in Belfast in December 1961, and in Scotland, of Henry Burnett in Aberdeen in August 1963.

In 1958 he had hanged the Scottish serial killer Peter Manuel. A legend arose that Allen’s son Brian – whose godfather was hangman Thomas Pierrepoint, Albert’s uncle – was his father’s assistant on that occasion. But a recent biography by prison officer Stewart McLaughlin reveals that Allen’s first wife Marjorie left him on that day and that Brian tried to contact his father in Glasgow to say his mother had walked out.

“The fact that Brian was still in Manchester trying to contact his dad finally puts an end to the story that he was the assistant executioner,” Stewart says.

Being an executioner was not a full-time occupation. Originally a lorry driver, Allen became a publican in Besses o’ th’ Barn, Manch­ester, and then worked for Singer Ltd as head of security. He left Singer in 1976 and went to live with his second wife Doris in Fleetwood, Lancashire, where he worked as a cashier for the Fleetwood Pier Company and played bowls in his spare time.

His role behind a bar conjures up visions of comic Al Murray’s “hang ’em and flog ’em” Pub Landlord. In a surreal twist, Allen had a real-life comedy connection. His granddaughter is actress and comedian Fiona Allen, who made her name in the TV comedy sketch show Smack The Pony.

Fiona, who is married to Michael Parkinson’s son Michael, has spoken about her macabre family background. “It’s as if I had two grandfathers,” she has said. “One was the sweet, lovely man who took me for walks on the beach, bought me sweets and toys and always had me laughing and giggling. The other one was the man employed to take lives for the Government.

“When I was a kid, everyone in the area knew what he did. I remember going round to my first boyfriend’s house for the first time and I tried to impress his dad by telling him I wanted to go on the stage. He looked up from his paper and said: ‘Going on the stage are you, lass? Well keep away from the trapdoor!’”

Harry Allen’s diary and tools of his trade are expected to fetch up to £5,000 when they are auctioned on November 11. A spokes­man for auction house Frank Marshall in Knuts­ford, Cheshire, said: “This is a very interesting piece of social history, particularly in light of the recent attention given to Pierre­point, who was Harry’s mentor. It’s a fascinating collection.”